1. Field of the Invention
The present invention relates to a nitrite type nitrification-reactive sludge, a production method therefor, a production apparatus therefor, a waste water treatment method and a waste water treatment apparatus. Here, the nitrite type nitrification-reactive sludge means an activated sludge in which ammonium oxidizing bacteria that oxidize ammonium nitrogen to nitrite have been accumulated with higher priority.
2. Description of the Related Art
A nitrating denitrification method is known as a method for treating waste water containing ammonium nitrogen, which is a method of nitrating (oxidizing) ammonium nitrogen to nitrate by nitrifying bacteria, and then reducing the nitrate to nitrogen gas by denitrifying bacteria to remove ammonium nitrogen.
However, in the above described nitrating denitrification method, the ammonium nitrogen (NH4) in the waste water is nitrified to nitrate (NO3) through nitrite (NO2), and a large quantity of oxygen needs to be supplied in the nitrification reaction. In addition, in the denitrification reaction of converting the nitrate to nitrogen gas, a large quantity of hydrogen donors (methanol, for instance) needs to be supplied.
Then, it is considered to stop the nitrification reaction of the ammonium nitrogen in a stage of nitrite and denitrifying the nitrite to nitrogen gas thereby to reduce the quantity of oxygen to be supplied in the nitrification reaction and the quantity of the hydrogen donor to be supplied in the denitrification reaction.
On the other hand, a method for treating a waste water, which includes denitrification treatment with anaerobic ammonium oxidizing bacteria, has drawn attention as a method for treating the waste water substitutable for a conventional nitrating denitrification method. This method includes nitriting the ammonium nitrogen in the waste water into nitrite, and simultaneously denitrifying the nitrite and the ammonium nitrogen in the waste water with the anaerobic ammonium oxidizing bacteria, and accordingly is more advantageous than the conventional nitrating denitrification method, in the points of not only being capable of reducing the amount of oxygen to be supplied in the nitrification reaction, but also needing no supply of the hydrogen donor in the denitrification reaction. However, in order to treat the waste water with the anaerobic ammonium oxidizing bacteria, the nitrification reaction of the ammonium nitrogen in the waste water needs to be stopped in the stage of nitrite.
For such a reason, some methods are proposed which are directed at producing a microorganism carrier which provides the nitrite type nitrification reaction of nitrating the ammonium nitrogen in the waste water into nitrite.
For instance, Japanese Patent No. 3788601 discloses a method for stopping the nitrification reaction of the ammonium nitrogen at the stage of nitrite, by accumulating only nitrifying bacteria suitable for the nitrite type nitrification reaction through heat treatment. This method subjects a carrier containing ammonium oxidizing bacteria which oxidize the ammonium nitrogen to nitrite and nitrite oxidizing bacteria which nitrite the nitrite to nitrate to heat treatment to deactivate the nitrite oxidizing bacteria and accumulate the ammonium oxidizing bacteria in the carrier with higher priority. By using the carrier, the nitrification reaction of the ammonium nitrogen in the waste water can be stopped at the stage of the nitrite.